Many different types of control valves have been provided in the past for controlling the flow of high pressure lubricant to machinery bearings through lubrication fittings. One type of control valve, sometimes referred to as a lubricant gun, includes a hand-held valve assembly that delivers a quantity of high pressure lubricant through an outlet extension tube having a coupler at the end thereof adapted to releasably fit over a lubrication fitting associated with the machine being lubricated.
These fittings are short male members with beveled ends to facilitate the location of the coupler. The coupler is a female fitting fixed to the gun's extension tube, and usually has a socket that receives and conforms in shape to the fittings so the coupler is sealed to the fitting during lubrication.
Automobiles are exemplary of machines that have this type of fittings for the chassis and wheel assembly bearings that require periodic lubrication. Because of the high viscosity of the lubricant and because of the presence of foreign material in the fittings and bearings to be lubricated, extremely high lubricant source pressure on the order of 2,000 PSI is required. In some cases, pressures as high as 9,000 PSI are encountered. If the operator inadvertently actuates the control valve when the extension coupler is not properly seated on the lubrication fitting, lubricant discharges from the coupler extension at a high velocity presenting a very serious danger to personnel in the area because it can readily penetrate human tissue.
To obviate or minimize this problem it has been proposed in the past that a restrictor be provided in the control valve outlet extension to reduce the flow rate from the coupler when the coupler is not properly positioned. This restrictor is disclosed and claimed in the co-pending Application of Joseph M. Stomper entitled "High Pressure Control Valve" Ser. No. 689,673, filed May 24, 1976, now abandoned, assigned to the assignee of the present invention. With this orifice or restrictor, the high velocity lubricant passing through the restrictor orifice when the coupling is not connected to a fitting dissipates in the extension tube and lubricant discharges from the coupler at a relatively low velocity, harmless to human tissue. While this restrictor is acceptable for many applications, it has been found that the restrictor tends to clog when using a source lubricant having entrained foreign material. ln such cases the user will frequently simply remove the restrictor to eliminate the clogging problem and then obviously the control valve resumes the capability of high velocity inadvertent discharge.
It is a primary object of the present invention to ameliorate the problem noted above in the prior art and provide a high pressure control valve restrictor assembly that is self-cleaning.